Bethlehem on Wednesday kicked off a $12 million sewer upgrade that aims to make the sludge lighter and less expensive to truck out of the treatment plant to landfills and other disposal sites.

The 9,000-square-foot bio-solids dewatering facility will include two centrifuge pumps that will wick more water from the sludge processed at the 62-year-old plant at 144 Shimersville Road. The project also includes improvements to the pump station.

"This project will improve and reduce maintenance costs and will reduce the volume of solid waste and improve the health and environment for our citizens," Mayor Robert Donchez said at a news conference at the plant. "And it will also reduce our carbon footprint."

The city secured a $1.25 million state grant for the project and will pay for the rest with a 20-year loan through the Pennsylvania Infrastructure Investment Authority.

Ed Boscola, the city's water and sewer resources director, estimated the project would save the city $300,000-$400,000 in energy, maintenance and landfill costs each year. That accounts for at least half of the city's annual debt payments for the project.

It's the third step of what could be a $75 million improvement plan that could span 20 years, depending on demand and funding.

The project comes as the city finishes a $10 million upgrade at the plant to the digesters, the cylindrical tanks. Two years ago, the city completed a $2.3 million upgrade to the aeration basin.

The city has 24,000 customer accounts in Bethlehem and Hanover Township, Northampton County. It also treats sewage in bulk from Bethlehem Township, Freemansburg, Hellertown and Lower Nazareth and Lower Saucon townships in Northampton County, and from Allentown, Fountain Hill and Hanover and Salisbury townships in Lehigh County.